Sewer flow hysteresis in trunk sewers – observations using improved velocity sensors

Abstract

Trials of transit time ultrasonic velocity sensors were found to significantly reduce measurement uncertainty due to “false signal noise”, from +10% for doppler sensors, down to +2% for transit time sensors. As a result of the improved measurement uncertainty, a hysteresis “loop – rating” phenomena has now been clearly identified for the first time, from measurements, and confirmed by calibrated model results.

Keywords:

• Hysteresis
• loop rating
• velocity sensors
• measurement uncertainty
• sewer flow gauging
• openc
• channels
• modelling

Additional information

Notes on contributors

Glenn McDermott

Born 1954, and graduating with honours in Civil Engineering from University of NSW in 1977, followed by a Masters degree in 1981. The research associated with the Master,s degree gained a National award for best engineering research paper in 1982, and the practical methods developed continue to be used and updated as part of National guidelines on rainfall and runoff modelling and flow estimation. Since graduation, 13 years have been as an employee with Sydney Water Corporation, and 13 years with private consulting companies, other government departments, or as a sole consultant. The main speciality of these works has been in the area of excellence in gauging and monitoring network designs and how these data are used in computer modelling of natural and man-made systems, for better planning of major system improvements. Some of the major projects he has been a key team member of are:- Sydney Sewer Ocean Outfalls planning (1983–84); Warragamba Dam Spillway Amplification (1987–88); Urban Flood Management Taskforce (1988); Narara Creek Flood Mitigation (1989); Sydney Clean Waterways Programme (1990–97); Sewerage Overflows Licencing Programme (1997–1998); Water allocation management plan revision programme on several NSW rivers (1998–2000). Just before leaving Sydney Water again in 2002, work was completed on new National sewer design standards for flow estimation, including recommendations for greater and better use of computer models and flow and rain gauges. Current employment is in private enterprise with Greenspan Technology, managing their Sydney office.

V Mohanathasan

Robert Stewart (Hyd. Cert.) has over 23 years measurement industry experience, specialising in the development and successful proving of clamp-on type transit time velocity sensors in closed pipes, now extended to open channel transit time type velocity sensors. Robert is a member of Sydney Water’s Monitoring services group. Roberts duties include equipment Research and Development, co-ordination of staff and projects, and operational duties. Robert has experience in the installation, operation and management of Water quality, water flow, water pressure, sewer flow, sewer velocity, pipe profiling, stormwater flow, Sewage Treatment Plant and rainfall sites througout the Sydney area for Sydney Water as well as extenal customers. Robert has also been a key member of interstate project teams involving installation, operation and managment of these projects. Robert has extensive experience with the editing and archiving of data using a variety of methods including HYDSYS. Robert has experience with level to flow and area rating tables for use in obtaining flow rates. Robert has trained people in the use of various Hydrograhic instruments and data loggers and is a competent and experienced trainer.

Robert Stewart

V Mohanathasan (BscEng. MEng) has over 17 years experience in mathematical and optimisation modelling, and has played a leading role in the development, calibration, use and maintenance of SWC’s trunk sewer models. He works in Sydney Water Corporation’s Asset Planning and Management Division.